/* scanner for a toy Pascal-like language */

%option noyywrap     
%{
/* need this for the call to atof() below */
#include <math.h>
%}

DIGIT    [0-9]
ID       [a-z][a-z0-9]*

%%

{DIGIT}+    {
         printf( "An integer: %s (%d)\n", yytext,
                 atoi( yytext ) );
         }

{DIGIT}+"."{DIGIT}*        {
         printf( "A float: %s (%g)\n", yytext,
                 atof( yytext ) );
         }

if|then|begin|end|procedure|function        {
         printf( "A keyword: %s\n", yytext );
         }

{ID}        printf( "An identifier: %s\n", yytext );

"+"|"-"|"*"|"/"   printf( "An operator: %s\n", yytext );

"{"[\^{}}\n]*"}"     /* eat up one-line comments */

[ \t\n]+          /* eat up whitespace */

.           printf( "Unrecognized character: %s\n", yytext );

%%

main( argc, argv )
int argc;
char **argv;
 {
 ++argv, --argc;  /* skip over program name */
 if ( argc > 0 )
         yyin = fopen( argv[0], "r" );
 else
         yyin = stdin;

 yylex();
 }
